Vehicle with an air cushion lifting system

ABSTRACT

A vehicle with an air-cushion lifting system having improved propulsion, stabilizing and control devices, said vehicle comprising: a platform equipped with flexible bands forming a plurality of skirts and especially a peripheral skirt, means for supplying air under pressure to the cushion formed under said platform by said bands, said flexible bands constituting longitudinal and transverse skirts under the platform, forming with the other said bands, and especially with said peripheral skirts, at least two chambers extending longitudinally side by side, and each capable of being supplied with air under pressure independently of the other chambers, the said chambers being in communication with each other; and air-actuated propulsion devices mounted on said platform. The vehicle is intended for travelling over rough or smooth surfaces, or land or over water.

[45] Apr. 15, 1975 United States Patent Paoli PMENIEUAPRISIQYS 3 a?? 542SHKET l UF 4 I VEHICLE WITH AN AIR CUSHION LIFTING SYSTEM The presentinvention relates to a vehicle in which a cushion of air provides thenecessary lift for its displacements, both on the ground and over water.

It is more particularly' directed to a system of cushion chambersensuring excellent stability during the displacement of a vehicle ofthis type.

It is also concerned with a simple. relatively cheap device which iswell adapted to the combined supply systems of an air cushion andpropulsion means. A device of this kind is quite suitable for theequipment of an air-cushion vehicle which is required to be ofarelatively modest size.

Vehicles have already been proposed which are in tended to move over theground and over water by means of a lifting cushion of air. This methodof lift avoids the traditional necessities for runways or roads. and isequally well adapted to the irregularities of the ground and to those ofthe swell or waves of an expanse of water.

A vehicle of this type essentially comprises a platform on which isfixed a flexible skirt which forms, under this platform, a chamberintended to be supplied with air under pressure from a source carried onthe platform, for example a motor-fan set; known propulsion devices withscrew propellers of ejection nozzles are also carried on this platformin order to ensure the displacement of this latter when it is supportedon this cushion of air.

Now, a first form of embodiment frequently adopted for such vehiclescomprises a simple peripheral skirt which, by reason of thepossibilities of random diffusion which it allows for the air of thebushion` necessitates large radial dimensions in order to give theplatform satisfactory stability.

Furthermore, a second form of embodiment cornprises a practicallyrectangular platform of acceptable dimensions and equipped with a numberof skirts, these skirts being arranged in the interior of the chamberformed by a main skirt, so as to form partitions in the cushion of airand thus to give good stability to the platform. However, these multipleskirts which encumber the lower face of the platform interfere with thedisplacement ofthe vehicle, especially over water in the case of wavesor swell, and in consequence result in a substantial loss of power.

The production, utilization and maintenance of the known air cushionvehicles are therefore expensive.

The invention proposes a remedy for these disadvantages.

It has mainly for its object a system of cushion chambers providingexcellent stability for an air cushion vehicle, even if the dimensionsof this latter are relatively small. A vehicle of this type comprisesessentially:

A platform equipped with skirts, and especially a peripheral skirt;

means for supplying air under pressure to the cushion formed under theplatform by the skirts;

conventional propulsion devices mounted on the platform.

According to the invention, the skirts form underneath the platform, atleast two chambers extending longitudinally side by side and eachcapable of being supplied by a source of air under pressure,independently of the supply sources of the other chambers.

In one remarkably' advantageous form of construction of a vehicleaccording to the invention, the lifting force is ensured simply by twolongitudinal chambers separated by a partition, the two chambers beingidentical and being connected to two also identical supply sources so asto form two cushion chambers communicating with each other by passagesarranged above the said central partition.

Tests have confirmed that such a system of lift applied to the platformof the vehicle gives this latter an excellent stability.

According to another characteristic feature of the invention, eachsource of air under pressure comprises a fan of the centrifugal type.

The particular characteristics of flow-rate and pressure of the currentof air supplied by a fan of this kind adapt themselves in a remarkablemanner to this method of lift on separate cushions. The directions ofthe variations of the delivery' of such a fan are always the reverse ofthose of the variations of the pressure of the flow of air, which canprovide, against the effects of rolling, transverse restoring coupleswhich are very desirable for the transverse stability of the vehicle. lnaddition, each longitudinal chamber, coupled in this way to a fan of thecentrifugal type, is advantageously equipped with at least onetransverse partition so as to create in the corresponding cushion,against the effects of pitching, differences of pressure which generatelongitudinal restoring couples, air passages being provided between thesaid chambers above the partitions.

According to another advantageous characteristic of the invention, thepropulsion means are constituted by discharge nozzles, respectivelyconnected to the centrifugal pans which ensure the supply of thelongitudinal cushion chambers.

The relative simplicity of such a combination of propulsion means withthe fans supplying the cushion chambers and the transversely-spacedarrangement of these chambers, is remarkably suitable for a very simplemethod of operation and steering of the vehicle on its cushion. lnconsequence, it renders possible inexpensive productions of such avehicle.

This combination is also favourable to the production of rapid, reliableand relatively economic transport vehicles for passengers, moreparticularly over water. The dimensions of such a vehicle mayfurthermore be relatively modest.

Finally, the invention relates to improvements in skirts of air-cushionvehicles. These improvements ensure good performance of the skirtsagainst obstacles, and prevent rapid or premature wear of these skirts,together with losses of power.

Other characteristic features and advantages of the invention will bebrought out in the description which follows below with reference to theaccompanying drawings, this description and these drawings being givensolely by way of example and not in any limitative sense.

In the drawings:

FIG. l shows in perspective and with parts broken away, an air cushionvehicle according to the invention;

FIGS. 2 to 4 represent respectively, on a smaller scale, in plan view,in transverse section and in longitudinal section, further views of thevehicle of FIG. l;

FIG. 5 is a view in perspective and to a smaller scale, of the vehicleshown in FIGS. 1 to 4;

FIG. 6 represents a plan view, to a smaller scale, of a skirt deviceprovided on the vehicle of FIG. 5;

FIG. 7 represents in cross-section to a larger scale, a detail of theskirt device of FIG. 6;

FIG. 8 represents a perspective view of an equipment apparatus for thedevice of FIG. 6;

FIG. 9 is a diagrammatic view in cross-section of an adjustable airdistribution device associated with a centrifugal fan capable ofequipping the vehicle shown in FIGS. l and 5;

FIG. l shows diagrammatically a longitudinal crosssection of the skirtdevice of FIG. 6'.

FIG. 11 represents a horizontal cross-section of a detail of the suctionopening of a centrifugal fan equipping the device of FIG. 9;

In the form of embodiment shown by way of example in FIGS. l to 4, therecan be seen three longitudinal spars la', lm, lg, arranged in paralleland forming between them equal distances, and assembled by their extremities on two cross-members 2v, 2r, so as to form a frame which hasthe general shape of a rectangle, the outer corners of this frame beingrounded.

These longitudinal members 1d to 1g and crossmembers 2v, 2r are tubularand their transverse sections are practically rectangular. It should bestated that this frame may be produced by utilizing glass fibre fabric,suitably applied on appropriate formers and impregnated with apolymerizable mixture of synthetic resins. The structure thus formed issufficiently strong and sufficiently light to be able to float on water`even when this frame carries the loads corresponding to the elements anddevices described below. This form of construction is appropriate to thewater-tightenss of the caissons formed by these longitudinal andtransverse members.

Rigid plates arranged edge to edge in the form of a flooring are fixedon the longitudinal members ld to lg and the cross-members 2i'. 2r ofthe frame so as to constitute a platform 3 on which is arranged acockpit 4, for example of the same type as the cabins of small pleasureboats or automobile vehicles. This cabin extends from the extremeportion of the platform carried by the cross-member 2v, slightly beyondthe central portion of the platform.

As shown in FIGS. 1 and 5, this cabin comprises front and side windowedportions, access doors 4a with longitudinal hinges, seats 4b (partlyshown in FIGS. l and 3), a driving station comprising a dashboard 4c anda lever 4d which will be referred to later.

In addition, two centrifugal fans 5d, 5g, identical with each other, arearranged at the other extremity of the deck 3, corresponding to thecross-member 2r. These fans are arranged symmetrically on each side ofthe central vertical plane of the longitudinal member 1m of theplatform.

These fans are mounted practically level with the rectangular framesformed between the longitudinal members ld, 1m, 1g so as to leavebetween tham on the flooring 3 a space for the mounting of amotor-gear-box set 6 carrying a transverse output shaft on theextremities of which the impellers of the two fans 5d, 5g are suitablykeyed.

Finally, the scroll of each fan 5d, 5g is equipped with shutterednozzles described later, and is partly connected to a rectangularopening 3a formed in the flooring of the platform 3 (see FIGS. 2 and 4).

Furthermore, as shown in FIG. l, a flexible band 7 produced by applyinga coating of plastic material such as rubber on a canvas having goodmechanical strength, is intimately fixed by its upper edge on theperiphery' of the platform 3. It thus has two side portions 7a', 7gcorresponding to the longitudinal members 1d and lg, and front portion7i' and rear portion 7r corresponding respectively to the cross-members2v, 2r.

This band is made-up of flat gores suitably cutout and assemblededge-to-edge so as to produce a curved transverse profile, as will beexplained later. The two ends of this band 7 will be intimately fixed toeach other.

It will be understood that this band 7 thus arranged in a continuousform, plays the part of a peripheral skirt element forming chambersunder the platform 3 which can be supplied with air by the fans 5d, 5g,in order to obtain a conventional lifting cushion for the vehicleconstituted by the cabin 4 and the platform 3 with floats (see FIG. 5).

It will be observed that in FIGS. l, 3 to 5 and 7, the positions of theband 7 and those of the bands described below correspond to theconditions of utilization of the vehicle on its cushion.

A further band 8 also continuous, practically flat and of the samenature as the skirt 7, is suspended here and there under the outer sidesof the longitudinal members ld, lg and the cross-members 2v, 2r, as willbe explained below. For normal conditions of use, this band 8 extendsparallel to the band 7 and its upper edge is maintained at a distance elfrom the bottom of the caissons and cross-members while its lower edgeis located practically at the level of the lower edge of the band of theskirt 7.

In addition, these bands 7 and 8 are assembled here and there on theedges of elements 14 arranged transversely. The assembly edges of theelements 14 are in the form of circular arcs which correspond to theprofiles intended to be given to the bands 7 and 8 in the position ofuse.

These elements 14 are made by cutting-out from a bers of a compositeskirt 7-8 capable of correct performance when the platform is carried byits air cushion.

verse space is formed between the lower edges of the bands 7, 8 of thisskirt in order to permit, for example, evacuation of any water which maybe engaged between these bands when the device is employed on a watersurface. However, between two adjacent spaces 14, these lower edges arejoined together at intervals by rivets.

However, the rounded portions of the skirt 7, 8 which correspond to thefour corners of the platform frame are also provided with spacers 16,similar to the spacers 14. The shape of these spacers is adapted to theprofiles which the corners of the skirt 7, 8 should have in the positionof use. Y

Finally, as shown in FIG. 7, the extremities of flexible cables 26formed by metal wires plaited to each other, are respectively fixed hereand there underneath the In this connection it will be noted that asmall transflooring 3 and on suitably selected parts of the band 8.These cables are preferably arranged in the transverse planes of thebracing members 14. ln the position of use, each cable 26 extends alongthe centre line of the chord of the arc of the edge adjacent to the band7, and ensures the suspension of the corresponding portion of the band8.

In addition, each cable 26 may be provided with a tension spring 26rwhich provides by its elasticity a restoring position ofthe portion ofthe skirt supported by this cable.

It should be noted that, in the case of the form of construction of theskirt from bands 7, 8 having relatively large widths, the height of thebracing panels 14 and 15 may be smaller than the width of the bands 7and 8. The lower portions of the bands 7 and 8 which are located belowthe lower edge of their bracing panels are then advantageouslyassociated with each other here and there by hoops 20 having the shapeof inverted U- members. These hoops are made of metallic wire havinggood mechanical elasticity and their arms are engaged in canvas sheathsformed vertically on the opposite faces of the two bands 7 and 8.

Furthermore, the two sides of the central longitudinal member lm carrytwo bands 9d, 9g, practically identical with the longitudinal portions8d, 8g, respectively suspended underneath the longitudinal members 1d,lg, as shown in FIG. 3. The width of these bands 9d, 9g is slightlysmaller than that of the band 8, and their ends are applied, withoutbeing fixed, on the front portion 8v and rear portion 8f of the band 8.

ln addition, bracing members l5 similar to the members 14 and having twosymmetrical edges in circular arcs, are also assembled transversely bystitching and sticking to the internal faces of these bands 9d, 9g, inorder to form a central longitudinal skirt.

This composite skirt 9d, 9g is also suspended from the platform bycables 26 which may be provided with tension springs 26r similar tothose described above. These cables are arranged in pairs in thetransverse planes of the bracing members l5. Each cable of one set isfixed at one extremity on the convex face of a band (for example 9d) andextends along the centre line of the circular arc ofthe profile of theother band (9d, 9g).

A suspension of this kind further ensures a small space between thebottom of the longitudinal member lm and the upper edges of the bands 9dand 9g.

Finally, two further sets of bands 17d, 18d, and 17g, 18g, similar tothe bands 9d, 9g but having a width of the same order as that of theselatter, are also fixed to each other by bracing panels 19 similar to thebracing members l5, in order to form two transverse partitions. Thesepartitions are freely suspended transversely between the longitudinalsides 8d, 9d and 8g, 9g of the above-mentioned composite skirts, bycables 26 which may be provided with springs 26r.

In addition, profiled elements vin the form of blades d, 13d and 10g to-g are respectively arranged transversely between the sides of thelongitudinal members 1d, lm on the one hand and the longitudinal members1m, 1g on the other hand. These blades have smaller heights than thoseof the sides of the longitudinal members la', lg, and their bottom edgesare located at the level of the bottoms of the longitudinal members.These heights are furthermore smaller as the blades are farther distantfrom the cross-member 2v and are closer to the part of the platformcarrying the fans 5d, 5g.

ln FIG. 7 there are again seen the longitudinal member Id and the side7d of the skirt. ln addition. the lower part of the plate 21 is fixed bya longitudinal articulation member 21a, to the outer side of thislongitudinal member. Its upper portion is subjected to the thrust of acompression spring 22 which is supported against the side of thelongitudinal member.

This plate 21 is fixed in an elastic manner (arrowsjl, FIG. 8) to asole-plate 23 by a conventional system of two sets of arms 24a. 24b,articulated respectively on the plate 2l, between each other and on thesole-plate 23 in the form of a lozenge. Central articulation members ofthis system are associated with each other by a tension spring 25 shownon the alternative perspective form of FIG. 8.

The dimensions, especially the length of the arms 24a, 24h, is adaptedto the distance formed between the side of the longitudinal member ldand that of the skirt 7d, so that the sole-plate 23 is applied againstthe inner face of the skirt so as to keep it away from the longitudinalmember.

The alternative form of FIG. 8 differs from that which has just beendescribed by the fact that the plate 21 comprises simply holes formounting by means of screws on the side of the longitudinal ortransverse member. It should be noted that such elastic devices aremounted at intervals along the outer sides of the platform frame.

ln FIG. 9, there is again seen one of the two openings 3a of theflooring 3 of the platform, and the fan 5g. This latter comprises animpeller 27 having a relatively' large diameter with respect to theradial dimension of its blades, and a cylindrical diffuser or scroll 28,the lateral wall of which practically encloses only three quarters ofthe impeller 27.

One of the extremities of this wall 28 is fixed on the front edge of theopening 3a, and the other end portion is constituted by two slightlycurved shutters 28a, 28b and an end shutter 28C. These three shuttersare respectively mounted on transverse pivotal shafts 01, 02, 03.

A curved cylindrical wall 29 is fixed by one of its extremities on thetransverse edge of the rear portion of the opening 3a. The otherextremity of this wall 29 is equipped with an articulation axis 04 for ashutter 29a which can sweep over an area practically adjacent to thefield of rotation of the blades of the impeller 27.

The rear portion of this wall 29 and the shutters 28a to 28C constitutean outlet nozzle towards the rear P and the shutter 29a separates theflow of air from the impeller 27 into two streams, respectively directedtowards the nozzle P and the opening 3a.

Another cylindrical air-guiding wall 30 is mounted transversely betweenthe longitudinal members 1m, 1g and also between lm and ld. This wallcomprises two shutters 30a, 30b, articulated transversely at 05 and 06,and another air guiding wall element 3l is arranged between these twoshutters.

Finally. a shutter 32 in the form of an airguiding blade, istransversely articulated at 07, inside the nozzle P which comprises theshutter 28b. lt should be stated that the lengths of the shutters 28band 32 and the relative positions of their pivotal shafts 02 and 07 areadapted to the height of the outlet section of this nozzle in order tobe able to close this latter.

In addition, the passage formed by the front edge of the opening 3a andthe wall 30 is also provided with a shutter 33, also articulated on atransverse axis 08.

Finally` a transverse cylindrical wall 34 is fixed on extensions ofthesides of the scroll and extends above the wall 28 of the end shutter28(l up to the top of this scroll, in order to form another nozzle F, towhich f`urther reference will be made later.

It will be indicated that the shafts of the shutters referred to abovemay be actuated by known means from the driving station in the cabin 4.In addition` the fan 5d is identical with the fan 5g described above andthe shutters of these two fans may be operated at will or insynchronism, so as to effect various driving and steering operationswhich are described below.

The positions of the shutters of the two fans being as shown in FIG. 9,and the engine 6 being running, two currents of air are establishedthrough the openings 3a so as to give two longitudinal air cushionsseparated by the partitions 9d and 9g. The blades l0 to 13 ensure theuniformity of supply to each of these cushions from the front to therear of the vehicle.

This uniformity of supply will ensure a uniform distribution of the airpressure on the various parts of the skirt 7, 8 which tends to take theshape of a balloon by virtue of the fixing effects of the bracingmembers 14 and the elastic cables 26, so as to produce a practicallyuniform lifting thrust from the various parts of the platform. Thislatter is thus raised and maintained at a height l1 above the ground,while the lower edge of the skirt 7, 8 has a spacing e2 with respect tothe ground, for the escape of air from the cushion (see FIG. 4).

The rate of flow is different on the two faces of the band 8, since thespeed of flow is smaller on the face associated with the bracing members14. In consequence, the air pressure is greater on this face than on theother face. This difference in pressure generates a force directeddownwards, the vertical component of which has the effect of stabilizingthe fixing point of the cables 26 on the band 8. This result isapplicable to relatively-high skirts equipped with sets of two cables,to which reference will be made later.

Simultaneously, two other currents of air escape through the two outletnozzles P so as to generate by reaction a thrust (arrowf2) ensuring thedisplacement of the vehicle.

The two shutters 21a can then be actuated so as to bring them, forexample, into the position A of FIG. 9, and to increase the flow-rate ofair from the cushion chambers to the detriment of the two currents ofpropulsion air, and thus increase the height l1 of"flight" of thevehicle with a view to adapting its displacement to the amplitudes ofthe irregularities of the ground. In this respect, it is also possibleto actuate the sets of shutters 30u, 30h, and also if so desired the twoshutters 33 in order to modify the air distribution between the frontand rear parts of the cushion for the purpose of maneuvres such asputting the nose up, to compensate for such irregularities.

Conversely, the two shutters 29a may be brought into the position B(FIG. 9) in order to reduce the height of flight or to increase thespeed of propulsion of the vehicle, but at each instant the two tailshutters 28(I may be actuated in order to regulate the outlet section ofthe nozzles P as a function of the output of the two fans, for thepurpose of obtaining a maximum propulsion thrust.

In addition, it is possible to actuate the shutters 32 in order toreduce the flow of air in its outlet nozzles P and in consequence thespeed of the vehicle. In this connection, the shutters 28b enable a partof these propulsion currents to be deflected towards the nozzles F so asto generate a thrust (arrowf3) which is obviously opposite to thepropulsion thrust (arrowj2), and thus gives a braking effect. Thisbraking may be reinforced by the action of the two shutters 28a afterthese latter have been opened, until a relatively rapid stopping of thevehicle is obtained.

Finally, the two sets of shutters 32 and 28b may be brought into theclosure position of the propulsion nozzles P and the two shutters 28amay be opened so as to provide a reverse travel of the vehicle.

These driving operations of the vehicle are obviously obtained byidentical and practically synchronized manoeuvres of the shutters of thetwo fans, and it is clear that different judiciously combined manoeuvresof the corresponding shutters of the two fans would cause turning orpivotal movements while running forward or in reverse. These evolutionsof steering may be effected in a remarkably flexible manner in view ofthe very elastic method of lift provided by the two cushions of theplatform of the vehicle.

In this connection, the cables 26 and their possible springs 26r operatein the same manner as elastic cables in order to permit variousmovements of their skirts.

In particular, the external skirts 7, 8 may be spaced apart towards theexterior and upwards in order to obtain a reduction in volume of thechambers, which facilitates the damping of shocks due to irregularitiesof surface.

In addition, the sole plates 23, by virtue of the articulations 21usefully accompany the band 7 in order to facilitate these displacementsof the outer skirt when such damping phenomena take place.

Furthermore, as shown in FIG. 10, when the front portion 7i' of theskirt comes into abutment against an obstacle (irregularity of ground ora wave on a water surface), the leakage of air from the portion of thecushion comprised between the front portions 7V, 8v and the partitions18d and 18g is reduced. In this way, the air pressure of these parts ofthe two chambers tends to increase, without influence on the operationof the two fans, which generates a restoring couple (arrow f4) andreestablishes the cushion.

It is also possible to provide suspension means, ad-

justable at will, for the partitions 17 and 18, in order to adjust thespacings e3, e4. The distance e3 is formed between the lower edge of teblades ll, l2 and the upper edge of the bands 17, 18, while the distancee4 is formed between the lower edges of these partitions and the ground.Their adjustments serve to modify the value of the above-mentionedrestoring couple.

ln addition, when the leakage of air from one of the sides 7d, 8d forexample is accidentally stopped by the effect of a wave, the output ofthe corresponding fan 5d tends to diminish and, taking into account theparticular characteristics of working of fans of the centrifugal type,the condition of operation of the fan 5d is modified so as to supply asmaller flow of air at a higher pressure. As the working condition ofthe other fan 5g has not varied, this results in a very large transverserestoring couple which rapidly re-establishes the righthand cushion.

Bands 9d, 9g may furthermore be associated by adjustable suspensionmeans with the longitudinal member lm in order to regulate the height oftheir upper edges with respect to the ground. These adjustments give arestoring couple which is approximately proportional to the inclinationwhich the apparatus may assume.

lt will be understood that the outputs of the fans,

their power and in consequence that of the motor, must be suited to theloads carried by the platform. ln this connection, particular featuresof vehicles similar to that of FIGS. 1 to 5 are indicated in the Tablebelow so as to more readily appreciate the possibilities which have beenreferred to.

- Pressure under the platform in cm.WG Speed of vehicle I4 to 25 em.14() km/hr 8 to l5 cm. U knt/hr The anomalies of operation of thecushion due to such incidents of travel are rapidly counterbalanced bythe exchanges of air which may take place under the platform between thepartitions. The two outer longitudinal members and the cross-members arefurther provided with holes lt in order to ensure the correct supply tothe roll of the skirt. ln addition, the thrust of the sole-plates 23enables the disturbing effects of obstacles, for example those of waves,to be reduced under the platform, as these effects may result in damageto the skirt.

Finally, it will be noted that the blades 10 to 13 ensure a circulationof air in the form of approximately vertical columns. Each distributionof the flow permits a limitation of the consequences of an accidentalleakage of air due to a local irregularity of the surface, such as anobstacle, a ditch or a wave. Such a leakage causes disturbance in onecolumn and results in a curvature of the other columns of air whichcreates an over-pressure acting to oppose their movement towards thisleakage.

This result could be amplified by the use of flexible baffles arrangedtransversely in staggered relation in each of the two chambers.

2 6() kg. 30 kg.

l 120 kg. so kg.

Mo. of cables 26 per bracer I4 Distance between braeers I4: 1.0() rn.

lt should be stated that it is possible to obtain over water high speedsof travel of the order of 300 km/hr without adversely affecting thestability of vehicles provided with cushion chambers of this kind and inconsequence, rapid and safe transport can be provided.

In addition, in order to obtain economical transport. it is obviouslynecessary to utilize as low a power as possible. This power is mainly afunction of the conditions of suction of the flow-rate of air which mustbe ejected by the propulsion nozzles P.

To this end, (see FIG. ll) the intake orifice of each fan 5d and 5g isequipped with a ring 35 comprising blades 36 which extend vertically.This direction is substantially perpendicular to the usual direction ofmovement of the vehicle.

The foregoing description makes it possible to under- These blades aredirected parallel to the axis of the stand that the method of lift ofthe vehicle on two longiimpeller 27 and are rigidly braced bystreamlined tudinal cushions: blades 36a arranged horizontally and fixedon the ring separated from each other; 35.

equipped with a transverse partition arrangement, Another blade 37 isarranged vertically facing each and blade 36 and in font of4 this latterwith respect to the j respectively supplied by fans of the centrifugaltype, axial direction of the ring 35. This blade is suitably argivesremarkable results of stability, irrespective of the ticulated on thering 35 and has a transverse section in obstacles which may arise on thepath of the vehicle. the form ofa gutter. Its concave face is directedin the especially over water. sense of movement towards the front of thevehicle so By reason of the effectiveness of these cushions, it is as toform a device similar to the conventional louvres possible to producevehicles of relatively' small size of aircraft wings which prevent thephenomena of dewithout interfering with these results, whereas knowntachment of fluid at high speeds. types of cushion result in a sizehaving a substantially By virtue of the leading edge in the direction ofgreater order of magnitude. movement of these moving blades, it ispossible by a juln addition, the combination of propulsion means fordicious adjustment of their angles of incidence to enforward and reverserunning, with the supply means for sure an excellent supply of the fans(arrows f5), even the two cushions, is well adapted to a moderate-costat high vehicle speeds, by virtue of acceptable pressure production of avehicle of this type. The means for drivlosses in the intake orifice ofthe fans. At such speeds, ing, steering and braking are constituted bysimple this device avoids the use of prohibitively large power.

shutters and the usual devices permitting good coordination of controlof the corresponding shutters.

lt should be stated that the moving blades 37 could be replaced by twofixed blades having leading wings substantially larger than those of theblades of FlG. 1l. Such blades would also ensure a correct operationv ofthe fans.

It is clear that it would not be outside the scope of the invention toreplace certain devices described above by other known means givingsimilar effects. For example, the shutter and nozzle devices of FIG. 4could replace those of FlG. 9.

Furthermore. a platform could be equipped with three or morelongitudinal cushion chambers. each chamber being similar to the chamberdescribed above and supplied from a fari of the centrifugal type`independently of the other chambers.

In addition, similar stability results would be obtained like thosedescribed above by supplying such chambers separately by means of fansfor which, at a predetermined speed of rotation, the pressure of theflow of air varies inversely with the flow-rate of this air, effects ofthis kind being ensured by centrifugal fans.

ln addition, in the case of a relatively long platform, there may beprovided, in the extension of longitudinal chambers of acceptable sizesuch as those referred to above, other similar chambers each associatedwith a supply means giving the advantages of fans of the centrifugaltype.

Finally, the devices formed by composite skirts suspended from aplatform, could be applied to the formation of a cushion based on knownsupply methods different from these described above. Such devices ensuregood performance of skirts and partitions when encountering variousobstacles.

ln this connection, in the case of skirts having a relatively' greatheight. tthe peripheral skirt is fixed to the platform by sets of twocables 26 with springs, fixed to the same point on the platform. Thisadvantageously avoids an excessive curvature of the external edges ofthe bracing members 14 fixed on the band 7, by providing for this edgetwo circular arcs of smaller radius. Each elastic cable 26 is fixed tothe band 8 by being located on the centre line of the chord of thecorresponding arc.

The invention having now been explained and its advantage justified by adetailed example, the Applicant reserves the exclusive right during thewhole period of the patent, without any limitation other than that ofthe terms of the appended claims.

What we claim is:

l. An air-cushion vehicle, comprising:

A platform equipped with flexible bands forming skirts, and particularlya continuous peripheral skirt said peripheral skirt comprising an outerband attached to said platform; an inner band spaced from said outerband at its upper edge and attached to said outer band at spacedintervals by vertically flexible bracing panels, said inner band beingfixed at intervals to said platform by suspension means and cables,

means for supplying air under pressure to the cushion formed under saidplatform by said bands;

propulsion devices mounted on said platform, said flexible bands underthe platform being longitudiy nal and transverse skirts forming withsaid bands and particularly said peripheral skirts, at least twochambers extending longitudinally side by side and being supplied withair each independently of the other chamber. said chambers being incommunication with each other, the skirts of said air cushion allowingcirculation of air under pressure from one chamber to the next forgenerating a force couple to restore said vehicle to a predeterminedequilibrium position after having been rolled to an inclined positionduring motion of said vehicle.

2. An air-cushion vehicle as claimed in claim l, in which said means forsupplying air to a chamber coniprise a fan of the centrifugal type andeach longitudinal chamber is equipped with at least one transverse skirthaving a smaller height than that of the other skirts.

3. An air-cushion vehicle as claimed in claim l, in which saidpropulsion means comprise nozzles respectively coupled to said meanssupplying air to the chambers of the cushion.

4. An air-cushion vehicle as claimed in claim 2, in which each said fanofa cushion chamber is coupled to a propulsion nozzle directed towardsthe rear and to a braking and reversing nozzle directed towards thefront.

5. An air-cushion vehicle as claimed in claim 4, in which each saidpropulsion nozzle is provided with means for regulating its outletsection.

6. An air-cushion vehicle as claimed in claim 1, and further comprisinga frame composed of three longitudinal members` identical with eachother, and two cross-members, said longitudinal and cross-memberscarrying a platform flooring and being arranged in the form of floats.

7. An air-cushion vehicle as claimed in claim 6, and further comprisingtwo identical longitudinal cushion chambers respectively associated withtwo identical fans and coupled to the same driving shaft, said chamberscommunicating with each other by spaces formed between said centrallongitudinal member and the central skirt carried by said centralmember.

8. A skirt device constituted by flexible bands, applicable to anair-cushionvehicle as claimed in claim l, in which one of said bandsextends parallel to said peripheral band and is associated in part hereand there with this latter by flexible means so as to constitute acomposite'peripheral akirt, said skirt being fixed at intervals to saidplatform by suspension means and by cables.

9. A skirt device as claimed in claim 8, in which further bands aresuspended longitudinally and transversely in the chamber formed by saidcomposite peripheral skirt, and are fixed to each other in pairs hereand there by flexible bracing members and to the platform by cables.

l0. A skirt device as claimed in claim 9, and further comprising pairsof longitudinal and transverse bands respectively associated with eachother at intervals by flexible means in the form of flexible bracingmembers having edges in the form ofa circular arc, so as to formlongitudinal and transverse skirts, the external skirt being stabilizedby the internal skirt.

11. A skirt device as claimed in claim 9, in which each said cable isfixed to a flexible band of a skirt and is arranged along the centreline of the chord of the arc of the other band of said skirt.

l2. A skirt device as claimed in claim l0, in which the bands of saidlongitudinal and transverse skirts are suspended from said platform bymeans for adjusting their height vabove the ground.

13. A skirt device as claimed in claim 8, and further provided atintervals with devices having soleplates and adapted to ensure anelastic thrust towards the exterior and upwards, on the upper parts ofsaid peripheral skirts.

14. A centrifugal fan comprising an impeller and a scroll casing adaptedto be utilized with an air-cushion vehicle according to claim 1, inwhich said scroll casing is equipped with a wall forming a propulsionnozzle. directed towards the rear and separating the flow of air fromsaid impeller into two streams directed respectively towards said nozzleand towards a cushion chamber.

15. A centrifugal fan as claimed in claim 14, and further comprisingmeans for regulating the flow-rates of the two streams to the nozzle andthe cushion chamber.

16. A centrifugal fan as claimed in claim 14, in which said scrollcasing comprises sides fixed to a wall forming a braking nozzle directedtowards the front, means being provided for supplying said nozzle fromthe flow of air delivered by said impeller.

17. A centrifugal fan as claimed in claim 16, in which the means forsupplying said braking nozzle are constituted by transverse shuttersforming part of a wall of said propulsion nozzle.

18. A centrifugal fan as claimed in claim 14, in which said propulsionnozzle is equipped with a shutter for regulating the outlet section ofsaid nozzle.

19. A centrifugal fan as claimed in claim 14, in which the scroll casingof each said fan comprises an orifice for coupling to an opening in thecushion platform, said coupling orifice being equipped with shutters fordistribution of air.

20. A centrifugal fan as claimed in claim 14, in which the inlet orificeof each fan is fitted with a ring comprising fixed blades directedparallel to the axis of the impeller of said fan and rigidly braced bystreamlined blades arranged horizontally and fixed on said ring togetherwith moving blades arranged vertically with respect to each fixed blade.

2l. An air-cushion vehicle. comprising:

A platform equipped with flexible bands forming skirts, and particularlya peripheral skirt;

means for supplying air under pressure to the cushion formed under saidplatform by said bands; propulsion devices mounted on said platform,said flexible bands under the platform being longitudinal and transverseskirts forming with said bands and particularly said peripheral skirts,at least two chambers extending longitudinally side by side and beingsupplied with air each independently of the other chamber, said chambersbeing in communication with each other, the skirts of said air cushionallowing circulation of air under pressure from one chamber to the nextfor generating a force couple to restore said vehicle to a predeterminedequilibrium position after having been rolled to an inclined positionduring motion of said vehicle, the

upper part of each said cushion chamber comprising streamlined elementsin the form of blades respectively disposed transversely between thesides of the external longitudinal members and the central longitudinalmember, said blades having heights smaller than those of the sides ofsaid longitudinal members and their lower edge being located at thelevel of the bottoms of said longitudinal members, said transverseblades being higher as they are further away from the air-supply meansfor said chamber.

22. An air-cushion vehicle as claimed in claim 2l, in

` which each said chamber is equipped with transverse shutterspermitting regulation of the air distribution in various parts of saidchamber.

23. An air-cushion vehicle, comprising:

A platform equipped with flexible bands forming skirts` and particularlya peripheral skirt;

means for supplying air under pressure to the cushion formed under saidplatform by said bands;

propulsion devices mounted on said platform. said flexible bands underthe platform being longitudinal and transverse skirts forming with saidbands and particularly said peripheral skirts. at least two chambersextending longitudinally side by side and being supplied with air eachindependently of the other chamber, said chambers being in communicationwith each other, the skirts of said air cushion allowing circulation ofair under pressure from one chamber to the next for generating a forcecouple to restore said vehicle to a predetermined equilibrium positionafter having been rolled to an inclined position during motion of saidvehicle. one of said bands extending parallel to said peripheral bandand being associated in part with this latter by flexible means so as toconstitute a composite peripheral skirt, said peripheral skirt beingfixed at intervals to said platform by suspension means and by cables,devices provided at intervals with soleplates and adapted to ensure anelastic thrust to` wards the exterior and upwards on the upper parts ofsaid peripheral skirts, said sole-plate devices comprising a platefastened by a longitudinal articulation member to the outer side of theperipheral longitudinal member, its upper part being subjected to thethrust of a compression spring supported against the side of saidlongitudinal member, said plate being fixed elastically to a sole-plateapplied against the internal face of said skirt by a system of two setsof arms respectively articulated on said plate, between each other andon said soleplate in the form of a lozange, the central articulationelements of this system being associated with each other by a tensionspring. =l l l

1. An air-cushion vehicle, comprising: A platform equipped with flexiblebands forming skirts, and particularly a continuous peripheral skirtsaid peripheral skirt comprising an outer band attached to saidplatform; an inner band spaced from said outer band at its upper edgeand attached to said outer band at spaced intervals by verticallyflexible bracing panels, said inner band being fixed at intervals tosaid platform by suspension means and cables, means for supplying airunder pressure to the cushion formed under said platform by said bands;propulsion devices mounted on said platform, said flexible bands underthe platform being longitudinal and transverse skirts forming with saidbands and particularly said peripheral skirts, at least two chambersextending longitudinally side by side and being supplied with air eachindependently of the other chamber, said chambers being in communicationwith each other, the skirts of said air cushion allowing circulation ofair under pressure from one chamber to the next for generating a forcecouple to restore said vehicle to a predetermined equilibrium positionafter having been rolled to an inclined position during motion of saidvehicle.
 2. An air-cushion vehicle as claimed in claim 1, in which saidmeans for supplying air to a chamber comprise a fan of the centrifugaltype and each longitudinal chamber is equipped with at least onetransverse skirt having a smaller height than that of the other skirts.3. An air-cushion vehicle as claimed in claim 1, in which saidpropulsion means comprise nozzles respectively coupled to said meanssupplying air to the chambers of the cushion.
 4. An air-cushion vehicleas claimed in claim 2, in which each said fan of a cushion chamber iscoupled to a propulsion nozzle directed towards the rear and to abraking and reversing nozzle directed towards the front.
 5. Anair-cushion vehicle as claimed in claim 4, in which each said propulsionnozzle is provided with means for regulating its outlet section.
 6. Anair-cushion vehicle as claimed in claim 1, and further comprising aframe composed of three longitudinal members, identical with each other,and two cross-members, said longitudinal and cross-members carrying aplatform flooring and being arranged in the form of floats.
 7. Anair-cushion vehicle as claimed in claim 6, and further comprising twoidentical longitudinal cushion chambers respectively associated with twoidentical fans and coupled to the same driving shaft, said chamberscommunicating with each other by spaces formed between said centrallongitudinal member and the central skirt carried by said centralmember.
 8. A skirt device constituted by flexible bands, applicable toan air-cushion vehicle as claimed in claim 1, in which one of said bandsextends parallel to said peripheral band and is associated in part hereand there with this latter by flexible means so as to constitute acomposite peripheral akirt, said skirt being fixed at intervals to saidplatform by suspension means and by cables.
 9. A skirt device as claimedin claim 8, in which further bands are suspended longitudinally andtransversely in the chamber formed by said composite peripheral skirt,and are fixed to each other in pairs here and there by flexible bracingmembers and to the platform by cables.
 10. A skirt device as claimed inclaim 9, and further comprising pairs of longitudinal and transversebands respectively associated with each other at intervals by flexiblemeans in the form of flexible bracing members having edges in the formof a circular arc, so as to form longitudinal and transverse skirts, theexternal skirt being stabilized by the internal skirt.
 11. A skirtdevice as claimed in claim 9, in which each said cable is fixed to aflexible band of a skirt and is arranged along the centre line of thechord of the arc of the other band of said skirt.
 12. A skirt device asclaimed in claim 10, in which the bands of said longitudinal andtransverse skirts are suspended from said platform by means foradjusting their height above the ground.
 13. A skirt device as claimedin claim 8, and further provided at intervals with devices havingsoleplates and adapted to ensure an elastic thrust towards the exteriorand upwards, on the upper parts of said peripheral skirts.
 14. Acentrifugal fan comprising an impeller and a scroll casing adapted to beutilized with an air-cushion vehicle according to claim 1, in which saidscroll casing is equipped with a wall forming a propulsion nozzle,directed towards the rear and separating the flow of air from saidimpeller into two streams directed respectively towards said nozzle andtowards a cushion chamber.
 15. A centrifugal fan as claimed in claim 14,and further comprising means for regulating the flow-rates of the twostreams to the nozzle and the cushion chamber.
 16. A centrifugal fan asclaimed in claim 14, in which said scroll casing comprises sides fixedto a wall forming a braking nozzle directed towards the front, meansbeing provided for supplying said nozzle from the flow of air deliveredby said impeller.
 17. A centrifugal fan as claimed in claim 16, in whichthe means for supplying said braking nozzle are constituted bytransverse shutters forming part of a wall of said propulsion nozzle.18. A centrifugal fan as claimed in claim 14, in which said propulsionnozzle is equipped with a shutter for regulating the outlet section ofsaid nozzle.
 19. A centrifugal fan as claimed in claim 14, in which thescroll casing of each said fan comprises an orifice for coupling to anopening in the cushion platform, said coupling orifice being equippedwith shutters for distribution of air.
 20. A centrifugal fan as claimedin claim 14, in which the inlet orifice of each fan is fitted with aring comprising fixed blades directed parallel to the axis of theimpeller of said fan and rigidly braced by streamlined blades arrangedhorizontally and fixed on said ring together with moving blades arrangedvertically with respect to each fixed blade.
 21. An air-cushion vehicle,comprising: A platform equipped with flexible bands forming skirts, andparticularly a peripheral skirt; means for supplying air under pressureto the cushion formed under said platform by said bands; propulsiondevices mounted on said platform, said flexible bands under the platformbeing longitudinal and transverse skirts forming with said bandS andparticularly said peripheral skirts, at least two chambers extendinglongitudinally side by side and being supplied with air eachindependently of the other chamber, said chambers being in communicationwith each other, the skirts of said air cushion allowing circulation ofair under pressure from one chamber to the next for generating a forcecouple to restore said vehicle to a predetermined equilibrium positionafter having been rolled to an inclined position during motion of saidvehicle, the upper part of each said cushion chamber comprisingstreamlined elements in the form of blades respectively disposedtransversely between the sides of the external longitudinal members andthe central longitudinal member, said blades having heights smaller thanthose of the sides of said longitudinal members and their lower edgebeing located at the level of the bottoms of said longitudinal members,said transverse blades being higher as they are further away from theair-supply means for said chamber.
 22. An air-cushion vehicle as claimedin claim 21, in which each said chamber is equipped with transverseshutters permitting regulation of the air distribution in various partsof said chamber.
 23. An air-cushion vehicle, comprising: A platformequipped with flexible bands forming skirts, and particularly aperipheral skirt; means for supplying air under pressure to the cushionformed under said platform by said bands; propulsion devices mounted onsaid platform, said flexible bands under the platform being longitudinaland transverse skirts forming with said bands and particularly saidperipheral skirts, at least two chambers extending longitudinally sideby side and being supplied with air each independently of the otherchamber, said chambers being in communication with each other, theskirts of said air cushion allowing circulation of air under pressurefrom one chamber to the next for generating a force couple to restoresaid vehicle to a predetermined equilibrium position after having beenrolled to an inclined position during motion of said vehicle, one ofsaid bands extending parallel to said peripheral band and beingassociated in part with this latter by flexible means so as toconstitute a composite peripheral skirt, said peripheral skirt beingfixed at intervals to said platform by suspension means and by cables,devices provided at intervals with sole-plates and adapted to ensure anelastic thrust towards the exterior and upwards on the upper parts ofsaid peripheral skirts, said sole-plate devices comprising a platefastened by a longitudinal articulation member to the outer side of theperipheral longitudinal member, its upper part being subjected to thethrust of a compression spring supported against the side of saidlongitudinal member, said plate being fixed elastically to a sole-plateapplied against the internal face of said skirt by a system of two setsof arms respectively articulated on said plate, between each other andon said sole-plate in the form of a lozange, the central articulationelements of this system being associated with each other by a tensionspring.